Installation And Grounding In Pipelines With Cathodic; Corrosion Protection - ABB ProcessMaster FEP611 Operating Instructions Manual

5.4.8 Installation and grounding in pipelines with
cathodic corrosion protection
The installation of electromagnetic flowmeters in systems with
cathodic corrosion protection must be made in compliance
with the corresponding system conditions.
The following factors are especially important:
1. Pipelines inside electrically conductive or insulating.
2. Pipelines completely or for the most part with cathodic
corrosion protection (CCP) or mixed systems with CCP
areas and PE areas.
— When installing an electromagnetic flowmeter in pipes with
insulating inner lining and free from foreign matter, it
should be insulated with grounding rings on the upstream
and downstream side. The corrosion protection potential
is diverted. The grounding rings upstream and
downstream of the electromagnetic flowmeter are
connected to functional earth (Fig. 29 / Fig. 30).
— If the occurrence of external stray currents is to be
expected in pipelines with internal insulation (e.g. in the
case of long pipe sections in the vicinity of power supply
units), an uninsulated pipe of approx. 1/4 x DN of length
should be provided upstream and downstream of the
flowmeter sensor in order to deviate these currents away
from the measuring system (Fig. 31).
Internally insulated pipelines with cathodic corrosion
protection potential
2 3 45
6 10
1
8
Fig. 29: Bolt screw view
1 Pipe flange 2 Insulating plate 3 Gasket / insulating ring
4 Grounding plate 5 Insulating pipe 6 Flange 7 Lining
8 Insulation 9 Flowmeter sensor
Install grounding rings on each side of the flowmeter sensor.
Insulate the grounding rings from the pipe flanges and connect
them to the flowmeter sensor and to functional earth. Insulate
the screw bolts for the flange connections when mounting.
The insulation plates and the insulation pipe are not included
in the delivery. They must be provided onsite by the customer.
2
6
9
7 6
2
1
Fig. 30: Flowmeter sensor with grounding plate and functional earth
A Connecting line for corrosion protection potential
screw bolts without grounding rings
1 Insulated pipe 2 Functional earth 3 Grounding plate
2
1) ≥ 4 mm Cu, not included in the delivery, to be provided onsite.
The corrosion protection potential must be diverted through a
connecting line
Mixed system pipeline with cathodic corrosion protection
and functional earth potentials
1 2
B
B
G11050
Fig. 31: Flowmeter sensor with functional earth
A Connecting line for corrosion protection potential
screw bolts without grounding rings
1 Insulated pipe 2 Bare metal pipe 3 Functional earth
2
1) ≥ 4 mm Cu, not included in the delivery, to be provided onsite.
This mixed system has an insulated pipeline with corrosion
protection potential and an uninsulated bar metal pipe
(L = 1/4 x flowmeter sensor size) with functional earth potential
upstream and downstream of the flowmeter sensor.
The Fig. 31 shows the preferred installation for cathodic
corrosion protection systems.
ProcessMaster FEP610, HygienicMaster FEH610 | OI/FEP610/FEH610-EN Rev. B 21
B
B
2
A
A
away from the insulated flowmeter sensor.
3
A
1
B
B
G11049
B Insulated
1)
2 1
B
B
G11048
B Insulated
1)